The concept of gate driver on array (GOA) is integrated a gate driving circuit of a TFT LCD on a glass substrate to drive the scanning of a liquid display panel. In comparison with conventional driving technology adapting chip on film (COF), GOA driving technology saves the manufacturing cost greatly and omits the Bonding process of COIF disposed on the side by gate. In the meanwhile, GOA driving technology is advantageous to promote the production capacity.
In general, there are two pull-down holding modules, which are disposed on each cascade of GOA driving circuits, operate by turns in order to prevent circuit failure that caused from a threshold voltages positive shifting of a switching transistor after the switching transistor of the pull-down modules encounter positive bias stress (PBS). However, in fact, positive shifting, about 10V, still remains and affects the threshold voltage Vth of the switching transistor in the pull-down module. This situation affects stability of the switching transistor and will affect display stability of liquid crystal panel.
Therefore, defects of present technology urgently require improvement.